The present invention relates to a semiconductor memory device, and more particularly to a data read-out circuit in a semiconductor memory device.
In a semiconductor memory device, a data signal which is read from a memory cell selected by address signals is amplified by a sense amplifier and then supplied to a data output control circuit. The data output control circuit generates at a data output terminal an output data corresponding to the read data signal.
In order to reduce power consumption, it has been carried out to shorten both a selection time of the memory cell and an enabled time of the sense amplifier. Even if the sense amplifier is changed to a disenabled state, the output data is required to continue to be generated at the data output terminal. For this purpose, a data latch circuit is provided between the sense amplifier and the data output control circuit. The data latch circuit latches the output signal of the sense amplifier and supplies this latched data to the data output control circuit. Accordingly, the data output control circuit continues to receive the read-out data even after the sense amplifier is disenabled. The output data thus continues to be obtained from the output terminal.
However, the data latch circuit requires an additional time interval during which it latches the output of the sense amplifier and drives the data output control circuit in accordance with the latched result. For this reason, a data read time (i.e., a period from a time point of the address input to that of the output data generation) is prolonged to deteriorate a high speed data read-out operation.